Hyundai Developing Diesel Engine That Runs On Gasoline!

Diesel fuel is powerful stuff, particularly when you compare it to
gasoline. Compared to regular 87 octane pump gas it has 30% more BTUs,
therefore more power to create heat energy. It also has more carbon
molecules than gasoline and that is one of the reasons large and expensive
after-treatment devices are fitted to diesel vehicles in the US. Those
costs, plus the continuing higher price of diesel technologies like
ultra-high injection pressures, multiple stage turbochargers, and
piezoelectric injectors is why everyone is looking at building more
efficient gasoline engines, or adopting alternative internal combustion
fuels like alcohol, DME, natural gas, or hydrogen.

Hyundai is researching a different direction, searching along the
theoretical fringes of alternatives like HCCI (Homogeneous Charged
Compression Ignition), which is very temperamental and hard to achieve, for
more efficient transportation motors. Their answer is similar to HCCI, but
the company thinks its answer is cheaper to produce, more reliable, and
delivers all of diesel’s attributes at a lower cost. Plus it’s
not voodoo; others are working on what has been called OttoDiesel after the
Otto cycle engine, the familiar gasoline fueled engine and, obviously,
Diesel. Some say GM has running prototypes, which we cannot confirm.

Regardless who is doing the work on these hybrid engines, all began
with some basics of modern internal combustion engines: diesel engines
operate at very high fuel injection pressures, 1800-2000 Bar, about 29,000
pounds per square inch. Fuel for diesels is directly injected into each
cylinder, all modern diesels are turbocharged, and they have relatively
high compression ratios. Comparative spark ignition gasoline powered
engines increasingly use fuel directly injected into the cylinders but have
far lower 100-200 Bar (1400-2900 psi) injection pressures. They also often
use turbocharging and have relatively lower compression ratios. You can see
that although they are very different, similarities are abundant.

Hyundai, together with Delphi and the University of Wisconsin have
developed a running prototype engine, currently based on a production
2.0-liter in-line four cylinder block, that uses both supercharging and
turbocharging to create a diesel engine that runs on gasoline. They call it
GDCI with PPCI. Which means gasoline direct compression ignition with
partially premixed compression ignition. Their engine interweaves the
similarities in internal combustion engines.

Stepping back from the heavy metal and technology, futurists say
that, in the next 10-30 years, because gasoline is so prevalent, and with
the increase in diesel fuel required for greater numbers of heavy duty over
the road engines, gasoline remains a fuel for the future.

OK, back to the metal and tech. In Hyundai’s PPCI engine, like
all internal combustion engines, fuel is injected—but directly into
the cylinder at a compression ratio of 14.8:1, and not until after Top Dead
Center where the piston starts moving down into the power stroke. They
claim that multiple injections after Top Dead Center result in diesel-like
efficiencies and no knock or pre-ignition. This is because an injection of
a minute amount of fuel barely after TDC creates sufficient energy to
pre-ignite the later injected fuel. It is a very, very lean combustion
process due to multiple high pressure injections of fuel. It is also clean
and frugal.

While that sounds simple, just squirt the fuel in later, it’s
not. The system requires both a supercharger to create early in-cylinder
pressures and a turbocharger, plus a large recirculated gas cooler (EGR
cooling), and an electrically controlled, constantly variable valve train.
Cost savings are achieved using a standard direct injection 200 Bar fuel
pump with matched piezoelectric injectors and fuel rail and existing
cylinder block.

This technology promises clean burning, low emissions transportation
with reasonable price per engine. It also produces more power per cubic
inch or centimeter and therefore a smaller, lighter, more fuel efficient
engine. Who says diesel, gas, or their marriage is dead?